The present invention relates to a brakeshoe for a shuttle brake on a loom, and more particularly to a brakeshoe which has a lining thereon that exerts a braking effect on the shuttle.
In conventional brakeshoes a rigid plate, some with and some without linings, is supported resiliently with respect to a rigid wall of a shuttlebox that lies in prolongation of the reed. A spring force or other forces acting on the resilient plate forces the shuttle towards the rigid wall thereby generating a braking force. The force varies with the applied force which grows from zero at the instant of first contact between the shuttle and the brakeshoe up to a maximum value which corresponds with complete retreat of the shoe in the presence of the shuttle in the shuttlebox. There is a problem of maintaining a constant force on the shuttle over long periods of time because of wear and fatigue of the springs. Furthermore, the braking force varies with the coefficient of friction between the surface of the shuttle and the counterfaces of the rigid and yielding walls. This coefficient of friction often experiences considerable alterations in service because it is determined by different influences such as the state of the surfaces, himidity of the air or temperature.
Since the speed of the entry of the shuttle into the shuttlebox can likewise fluctuate the impact against the stop which defines the end position of the shuttle takes place with a varying degree of violence. Often the shuttle bounces off the stop so that the end position of the shuttle is not constantly the same. This has adverse affects on the succeeding throwing of the shuttle, and may also lead to difficulties in changing the spool.
As a remedy it has already been proposed (Swiss Pat. No. 512,609) to have a flywheel mass accelerated first of all by the shuttle and to make use of the energy imparted to the flywheel mass by the shuttle for forcing the shuttle up against a stop, so that the shuttle always reaches the same brake position against the stop. As a result, a correct and consistent position of rest of the shuttle takes place. One problem with such a device is it requires costly mechanism with moving components.